Variable sound level buzzer having a pole piece with an angled face



Aug. 25, 1970 H g WEST 3 525,992

VARIABLE SOUND L BUZZER HAVING A POLE PIECE WITH ANGLED FACE Filed Ap 5, 1967 INVENTOR HAROLD E. WEST BY flan/ $5 A TORNEY United States Patent 3,525,992 VARIABLE SOUND LEVEL BUZZER HAVING A POLE PIECE WITH AN ANGLED FACE Harold E. West, Du Quoin, Ill., assignor to P. R. Mallory & Co., Inc., Indianapolis, Ind., a corporation of Delaware Filed Apr. 3, 1967, Ser. No. 627,733 Int. Cl. G08b 3/10 US. Cl. 340388 7 Claims ABSTRACT OF THE DISCLOSURE A rotatable pole piece for the armature of a variable buzzer has a surface cut at an angle to the axis of the pole piece to give an elliptically shaped biasing surface for the vibration leaf of the armature. Stop means are provided to prevent excessive rotation of the pole piece.

This invention is an improvement over existing types of variable sound level buzzers. For the most part, prior art variable buzzers depend on a threaded screw within a pole piece which is advanced or retarded by a rotary motion of a lever or shaft so as to engage the armature tongue and permit, or stop, it from vibrating.

To cover the many varied applications of customer requirements, it is necessary to have a buzzer which will readily operate with either clockwise or counterclockwise rotation, and also with an arc rotation of the shaft or levelover a range of approximately 70 to 120 degrees. The threaded screw method would then require screws of various non-standard pitch made in both left and right hand thread.

The present invention is concerned with a variable buzzer which does not use the threaded screw design, and has as one of its objects the provision of a variable buzzer wherein a rotary pole piece Will easily operate in a clockwise or counterclockwise direction.

Another object of the invention is the provision of a variable buzzer wherein the arc rotation of the pole piece can be set between 70120.

Another object of the invention is the provision of a variable buzzer wherein the amplitude of vibration of the armature is varied in accordance with the distance between the means to bias the armature and the ends of the vibrating leaf of the armature.

Still another object of the invention is the provision of a variable buzzer which utilizes a pole piece having an angular surface for biasing the armature of the buzzer.

Still another object of the invention is to provide a variable buzzer having stop means for preventing excessive rotation of the pole piece during setting of the pole piece.

Another object of the invention is to provide a variable buzzer wherein the stop means comprises a pin extending through a shaft extension of the pole piece, the pin being adapted to engage tang means formed in a base plate.

Yet another object of the invention is the provision of a variable buzzer wherein the stop means comprises a pin formed in the pole piece and being adapted to engage a step in a bushing through which the pole piece is extended.

With the above and other objects in view, which will appear as the description proceeds, this invention resides in a novel coil bobbin substantially as described herein and more particularly defined by the appended claims, it being understood that such changes in the precise embodiment of the invention here disclosed may be made as come within the scope of the claims.

For illustrative purposes the invention will be described with reference to the accompanying drawings in which:

FIG. 1 is an exploded view showing the various rela- 3,525,992 Patented Aug. 25, 1970 tionship of parts of one embodiment of the variable buzzer of the invention;

FIG. 2 is a front view of the same embodiment of the buzzer;

FIG. 3 is a cross section taken along the line 3-3 of FIG. 1;

FIG. 4 is a front view in partial cross section of another embodiment of the novel buzzer; and

FIG. 5 is an exploded view showing the relationship of the pole piece and its bushing used in the embodiment of FIG. 4.

Generally speaking, the objects of the invention are accomplished by providing a variable buzzer wherein the amplitude of vibration of the armature is varied in accordance with the distance between the means to bias the armature and either of the ends of the vibrating leaf of the armature and further by providing a stop means to limit the setting of the armature biasing means. More particularly, with regard to the armature biasing means, the pole piece of the buzzer of the present invention is formed from a cylindrical shaft having an ellipitical surface at one end thereof to bias the vibration leaf of the buzzer armature so as to control the amplitude of vibration of the armature.

With particular regard to the stop means of the buzzer of the present invention, the amount of setting or are rotation of the pole piece so as to vary the amplitude of the armature, and thus the noise level of the buzzer, is limited in one embodiment by tang means formed in a base plate, the tang means being adapted to engage a pin extending through a shaft extension of the pole piece. In another embodiment the stop means comprises a pin extending from the pole piece and being adapted to engage a step formed in a bushing through which the pole piece is carried.

Referring now to FIGS. 1, 2 and 3, an armature 11 of the variable buzzer 10 is made up of U-shaped member having a base 12 and sides 13 and 14. As will be hereinafter described, side 13 serves as the vibrating leaf of the armature and is the principal source of the noise for the buzzer. Disposed within the armature is coil bobbin 15 having a wire winding 16 disposed between retaining runs 17 and 18, and further having a bore 19 and electric terminals 20 and 21. Pole piece 22 is carried by bushing 23 through the bore 24 of the bushing, the bushing being snugly fitted into bore 19 of the bobbin. The whole assembly is staked to base plate 25 through spring cup washer 26. Shaft extension 27 is snugly fitted to the shank portion 28 of the pole piece and is further held by pin 29 which extends through aperture 30 of the extension and aperture 31 of shank portion 28. Thus the pole piece, the armature and the bobbin are frictionally held against rotational movement against base plate 25 by the cup spring washer 26 biasing the flange 32 of the bushing 23 against the retaining rim 18 of the bobbin 15. Shaft extension 27 has a recessed potrion 27' for carrying a knob (not shown) for manual rotation of the shaft.

The sound produced by the buzzer is primarily due to the striking of the armature against the pole piece 22.

The noise level of the buzzer is controlled by biasing the amplitude of vibration of side 13 of the armature 11; that is, the vibrating leaf 13a of the armature. This is accomplished by providing a biasing means 40 for the armature wherein the location of the biasing means can be set such that the distance between either of the ends 13' and 13" and the biasing means 40 can be varied such that the amplitude of vibration of the vibrating leaf 13a is varied. Thus, in the present invention, the pole piece 22 has a cylindrical shaft head portion 33 of larger diameter than the shank portion 28 the front face 34 of which is formed at an angle to the axis of the pole piece 22 so as to form an elliptical surface. Thus as is more clearly 3 shown with reference to FIGS. 2 and 3, rotation of th pole piece 22 through manual rotation of shaft extension 27 causes the area A, which is the portion of the front face 34 biasing the vibration leaf 13a, to change its distance relationship between either of the ends 13' and 13" of the leaf. Since end 13' is relatively fixed, the change in position of the area A will change the amplitude of the vibration leaf 13a.

It should be understood, that the biasing means 40 need not be of the type shown in the present embodiment and that other means could be employed without departing from the basic concept of varying the distance between either of the end portions 13' and 13" and the biasing means. Thus, for example, the surface 34 of head portion 33 could be formed normal to the axis of the pole piece 22 with a pin being extended from the surface 34 as a substitute for the area A presently shown. As another example, a pin, constructed independently of the pole piece, could be slidably arranged so as to permit the pin to engage the leaf 13a at various distances from the fixed end 13.

In order to prevent excessive rotation of the shaft extension 27 when setting the armature biasing means 40, stop means 35 has been provided. In the embodiments of FIGS. 1 through 3, the stop means 35 comprises tang means 37 and 38 formed in base plate 25 adapted to engage pin 29. Rotation of shaft extension 27 causes pin 29 to engage one of the tang means thus stopping further rotation. The setting of such stop means are usually determined by customer demand.

FIGS. 4 and show another embodiment of the buzzer wherein different stop means are employed. As shown in FIGS. 4 and 5, the stop means 35 in this embodiment comprises a pin 39 adapted to engage step 41 formed in bushing 23. With this stop means, shaft extension 27 is press fitted to the shank portion 28 of pole piece 22.

- Functionally, the variable buzzer of the present invention provides a means of biasing the armature so as to control the noise level of the buzzer wherein the biasing means is shifted in relation to the ends of the vibration leaf of the armature. This is opposed to the commonly used screw type biasing means wherein the means is advanced or retarded from the vibration leaf. The two embodiments of the stop means limits the amount of variation in the buzzers noise level.

The variable buzzer of the present invention, as hereinhefore described in one of its embodiments, is merely illustrative and not exhaustive in scope. Since many widely different embodiments may be made without departing from the scope thereof, it is intended that all matter contained in the above description and shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

. What is claimed is:

1. A variable sound level buzzer comprising:

(a) a base plate,

(b) a U-s'haped armature one of whose sides serves as a vibration leaf and a coil bobbin disposed within said armature,

(c) a rotatable pole piece extending through said bobbin,

- (d) said bobbin, pole piece, and armature staked to said base plate,

. 4 (e) said pole piece including a cylindrical shank portion and an enlarged head portion at one end thereof, said enlarged head portion including a biasing face cut at an acute angle to the axis of said pole piece to bias the amplitude of said armature,

(f) and arotatable shaft extension extending from said pole piece at the end opposite said enlarged head portion for manually setting the bias of said biasing face.

2. A variable sound level buzzer according to claim 1 wherein stop means are included to prevent excessive rotation of said, pole piece while its biasing face is being set.

3. A variable sound level buzzer according to claim 2 in which said stop means comprises a pin extending through said shaft extension and tang means formed in said bias plate engaging said pin upon rotation of said shaft extension.

4. A variable sound level buzzer according to claim 2 in which said stop means comprises a pin extending from the head portion of said pole piece adapted to engage a step formed in a bushing carried by said coil bobbin through which said pole piece is extended.

5. A variable sound level buzzer comprising:

(a) a base plate,

(b) a U-shaped armature and a coil bobbin disposed within said armature, p

(c) a rotatable pole piece including a shank portion extending through said bobbin and an enlarged head portion disposed between said bobbin and the side of said armature acting as the vibration leaf of said armature, said enlarged head including an elliptical biasing surface adjacent and facing saidvibration leaf,

(d) a shaft extension snugly fitted to and'extending from said shank portion of said pole piece,

(c) said armature, coil bobbin and said pole piece staked to said base plate through a spring'cup Washer surrounding said shaft extension, said washer held against said base plate by said shaft extension, and

(f) stop means to prevent excessive rotation of said shaft extension means.

6. A variable sound level buzzer according to claim 5 in which said stop means comprises a pin extending through said shaft extension and tang means formed in said base plate engaging said pin upon rotation of said shaft extension.

7. A variable sound level buzzer according to claim 5 in which said stop means comprises a pin extending from the head portion of said pole piece adapted to engage a step formed in a bushing carried by said coil bobbin through which said pole piece is extended.

References Cited UNITED STATES PATENTS 2,658,194 11/1953 Kalin et al 340388 X 3,015,093 12/1961 Septer 340-388 X 3,345,627 10/ 1967 Herst et al 340-388 X HAROLD I. PITTS, Primary Examiner 4 US. Cl. X.R. 340-466, 384, 391 

